Classifier



H. HARDINGE Nov. 15, 1938.

CLASSIFIER Filed Jan. 11, 1956 4 Sheets-Sheet 1 om mu E We N m R A H a wo L R A H H. HARDINGE Nov. 15, 1938.

CLASSIFIER Filed Jan. 11, 1936 4 Sheets-Sheet 2 3mm HARLOWE. HARD NGE H.HARDINGE Nov. 15, 1938.

CLASS IFIER Filed Jan. 11, 1956 4 Sheets-Sheet 3 gwuc/wtm? HAR LOWEHARDI NGE W k. W

H. HARDINGE Nov. 15, 1938.

CLASSIFIER Filed Jan. 11, 1956 4 Sheets-Sheet 4 HARLOWE. HARDINGEPatented Nov. is iass UNITED STATES CLASSIFIER Ha'rlowe Hardinge, York,Pa., assignor to Hard- Y inge Company, Incorporated, York, Pa acorporation voi! New Yorlr Application January 11, 1936, Serial No.58,735

10 Claims.

This invention relates to apparatus of the type used for separatingvarious kinds of materials, and more particularly to the type ofapparatus usedin the metallurgical and other industries for 5,classifying purposes.

More specifically classifiers of the type falling within the scope ofthe present invention find use in almost every metallurgical operationwhere a mill grinds ores. The devices are also used for a 10 great manyindustrial purposes and may be used to wash sands, and other minerals.The devices may also be used in connection with grinding mills wherethey act in the capacity of classifiers which pass on as a productmaterial of a given 15 fineness but which returns the oversize materialfor further grinding.

An object of the invention is to provide an improved classifier by whicha close separation of materials may be obtained and in which the prod-20 not is uniformly fine and the oversize is clean in that it contains aminimum amount of fines which should go out with the product.

Another object of the invention is to provide an improved classifier inwhich the oversize material 5 is discharged from the main classifyingchamber with a minimum amount of wash water.

Another object of the invention is to provide an improved classifier inwhich the oversize material moving through the main classifying chamber3 is dewatered to a greater extent than was possible in prior devices ofa similar nature, and in which the water removed from theoversizematerial adjacent the discharge end of the main classifyingchamber can readily flow backwardly through 35 said chamber withoutcarrying with it a preponderance of oversize material.

Another object of the invention is to provide an improved rotary wetclassifier in which the oversize material is'propelled through a mainclassify- 40 ing chamber against a countercurrent of wash --water bymeans of a screw fiight of varying pitch and height which squeezes theoversize material as it approaches the discharge end of the classifler,and in which slots are formed in the portion 45 of the screw flightadjacent the discharge end of the classifier through which surplus-washwater squeezed from the oversize material can readily flow back into themiddle portion of the classifying chamber without carrying apreponderance 50 of oversize material with it.

' Another object of theinvention is to provide an improved classifier ofthe character mentioned, which is simple in construction, and reliableand exact in function under all conditions of service. 55 The inventionalso comprises certain new and useful improvements in the construction,arrangement and combination of the several parts of which it iscomposed, as will behereinafter more fully described and claimed.

In the accompanying drawings:-

Figure 1 is a vertiial longitudinal section of a classifier embodyingthe invention;

Fig. 2 is a transverse section taken on the line 2--2 of Fig. 1, lookingin the direction of the arrows;

Fig. 3 is an elevation of the oversize material discharge end of theclassifier, showing the slots in the portion of the screw flightadjacent this end of the device;

Fig. 4 is a view similar to Fig. 3, showing the slots equipped withmembers for varying the area thereof;

Fig. 5 is an enlarged view. partly in section, of a portion of thestructure shown in Fig. 4;

Fig. 6 is a horizontal section taken on the line Fig. 7 is a section ofthe oversize material discharge end of a classifier having elevating anddewatering buckets; and

Fig. 8 is a section taken on the line B8 of Fig. 7.

Referring to the drawings, the classifier comprises a main body portionor drum' II which is preferably mounted for rotation with the axis ofthe drum inclined with respect to the horizontal, as shown in Fig. 1,said drum being supported on a suitable base or frame i2.

For the purpose of rotating the drum ii, any suitable mechanism may beutilized. In the present instance the driving mechanism is shown asincluding an electric motor [3 which is operatively connected throughgears it, to a chain driving means l5 of any approved construction.

For convenience the left hand end of the drum ii, as illustrated in Fig.1, will be referred to as the front end and the right hand end of thedrum I i will be referred to as the rear end.

The right hand or rear end of the drum ii is the end through whichmaterial to be classified is fed into the drum, and the left hand orfront end is the end through which the oversize material is discharged-As shown in the present embodiment of the invention the axis of the drumii is inclined upwardly from right to left.

The material is adapted to be delivered into the classifier by means ofa chute or trough [6 which terminates at a suitable distance from theright hand or rear end of the drum I l.

The right hand or rear end wall ll of the drum mounted an annular bandIt.

The W of the band It is to provide an inlet opening for the classifier,and said band is so formed as to provide a lip over which the fines andwater or other liquid, either as a wash or that enters with the feed,are discharged from the classifier. The fines and water or otherliquid'discharged from the classifier fall into a trough 2| and arethereby carried away from the device.

For the purpose of conveying material from the right handor feed end ofthe drum towards the left hand or front end thereof and also for turningthe material over in the water within the drum means in the form of ahelical trough or screw flight 2| are provided.

The helical trough or screw flight 2| .comprises a metal band arrangedaround the inner wall of the drum II in thei'orm ofascrewwhichiscoextensive with said drum.

The height of the metal band 2| varies from end to end, said band beingof considerably less height at the right hand or feed end of the drum I,than at the left hand or discharge end of said drum, so that the helicaltrough or screw flight will gradually increase in depth from the rearend toward the front end of the drum II.

In order to provide for a squeezing action of the material passingthrough the drum II, the pitch of the band 2| is varied from one end ofthe drum to the other. That is to say, the convolutions of the band 2|are so formed that the helical trough is considerably narrower at theleft hand or front end than at the right hand or rear end ofthedrum Theconstruction and arrangement of the band 2| is such that a series ofpockets or compartments are formed for containing the material, thecompartment at the right hand or rear end of the drum beingcomparatively broad in width and shallow in depth, as indicated at 22,Fig. 1, and the compartment 23 at the left hand or front end of thedrumbeing comparatively narrow in width and high in depth, and also beingless in cross sectional area than the compartment 22. The intermediatecompartments 24, 25, 28 and 21 progressively change in cross sectionaldimensions. I

The manner in which the helical band is constructed is clearly shown inFig. 2, and as there shown said band may be formed of a series of platescut from sheet metal of suitable gauge and fastened together and securedto the wall'of the drum II by any desired means, such as welding,riveting, or the like.

Preferably the edge of the helical trough 2| abutting the wall of thedrum should be made integral with the wall of the drum, so as to preventthe passage of water and fines along the inner surface of the drum.

The portion of the helical trough nearest the oversize discharge end ofthe drum I I, is formed an opening" having a discharge lip 8| for theoversize material.

The material discharged from, the front end of the classifier falls intoa trough I2 and is thereby carried away from the apparatus.

Projecting through the opening til, is a pipe 23, through which washwater is supplied to the classifier.

In operation, assuming that the classifier is charged with material andwater and the drum I is being rotated through the operation of the motorit, each of the compartments 22, 24, 25, 28,

21 and 23, between the screw flight or helical trough 2|, will containvarying quantities of material.

The water line of the classifier is normally above the rear dischargeopening provided by the lip It, as indicated by the broken line, Fig, 1,and since it is customary to have the classifier in a slightly tiltedposition with the rear end lower than the front end, the direction offlow of water will be towards the rear end even though no extra washwater is introduced into the classifier through the pipe 23.

The rear end'portion of the classifier as defln by the compartments 22and 24 and the zone above them, functions as a primary settling chamber.During the operation of the device the coarse or oversize material willsettle in the bottom of the drum II, and the finer and other materialwhich may have a tendency to float or is carried in suspension in thewater will be carried out of the classifier by the water which passesover the lip It.

The oversize material which settles in the bottom of the drum II isforced, through the action of the helical trough or screw flight 2|,towards the left hand or discharge end of the drum, the material beingconstantly turned over by the ratation of the drum and the action of thehelical trough.

In its forward movement through the drum I, the oversize material comesin contact with cleaner and cleaner wash water, and as the materialturns'over, the finer particles which are disposed between the coarserparticles are liberated, and the wash water carries these particles offines with it towards the overflow or rear end of the classifier. Inthis way the water passing from the front end of the classifier towardsthe rear end washes the coarse particles clean of fines, dirt, slimes,etc.

Due to the construction and arrangement of the parts comprising thehelical trough or screw flight 2|, the depth of material contained inthe successive compartments between the convolutions of the helicaltrough varies from right to left, as has heretofore been described, sothat, as the material moves toward the discharge end of the classifier,a squeezing action is gradually imparted to the material and theoversize is condensed or compacted. This condensing of the oversizematerial is effected by the elimination of the finer material by thewashing action and overflow over the top of the helical trough as thecross section of said trough becomes smaller towards the discharge end3| of the apparatus.

The purpose in so constructing the helical trough 2| is to build up thesuccessive masses of material, so that when the material enters the lastzone, as defined by compartment 2!, the ratio of water to solids thereinis considerably less than that in the rear or feed end of theclassifier.

.Another advantage resulting from constructing the helical trough 2| insuch a manner is that the water, in flowing from left. to right throughthe drum H, is caused to pass from one compartment to the next in aseries of cascades, and in so doing the water carries with it the finermaterial which becomes exposed as the oversize material is turned overas it is worked toward the discharge end.

As shown in Fig. 1, the height of the helical trough betweencompartments 23 and 21 is above the level of the water in theclassifier, so that wash water flowing from compartment 23 is caused tofall in the'form of a cascade into compartment 21. Furthermore, theheight of the portion of the helical trough between compartments 21 and26 is considerably higher than the height of the portion of the helicaltr ugh which gradually lower towards the rear end .of the classifier,when the level of the water in the drum II is lowered, additionalcascades will be formed.

Also, should the oversize discharge or left hand end of the classifierbe elevated to a position higher than that illustrated in the drawings,this cascading effect can be produced without decreasing the amount ofwash water admitted to the classifier, since the rear or right hand endof the drum U will be so much lower than the left hand or oversizedischarge end of the drum, that the level of the water in the drumwillnot extend as fartcward the left as illustrated in Fig. 1, with theresult that additional portions of' the helical trough 2| will projectabove the water.

Since the screw flight or helical trough 2| terminates at the left handend of the drum H, the material will be discharged from the compartment23 over the discharge lip 3| and from thence fall into trough 32.

When the classifier is operated at normal capacityeach of thecompartments between the helical trough 2| will be filled with materialand wash water, and since the material is squeezed or compacted in theseveral compartments by the action of the helical trough, it is ofadvantage to dewater the material as it approaches the oversizedischarge end of the classifier, so that a minimum amount of water willpass out of the classifler with the oversize material.

Therefore, according to the present invention, the left hand portion ofthe helical band 2| is formed with the series of notches 28, heretoforereferred to.

The purpose of these notches or slots 28 is to permit surplus water inthe compacted material in the high portion of the classifier to drainback into the more saturated and loosely compacted material in the lowerpart of the classifier,

It will be noted by referring to Fig. 1, that the last flight to theleft of compartment 23, is much higher than the discharge lip 3|, sothat the oversize will be forced out a large part of the revolution ofthe drum ll, rather than at only one point. The water in the materialbeing discharged drains back into the drum through the slotted openings28, and if so desired the area of these openings can be varied oradjusted to suit varying conditions and various kinds of material.

As'shown in Figs. 4, 5 and 6, one manner of adjusting the sizes of theslots 28 is to employ an adjustably mounted plate 34 for each slot.

The plates 34 are preferably formed of 2. rectangular piece of sheetmetal or plate steel.-

Attaching elements which may be in the form of bolts 33 are mounted inopenings 38 formed in the helical band 2| adjacent one edge of thenotches 28.

The plates 34 are formed with a series of open- 5 or slots 28 andthereby reduce the size of said slots, and in order to prevent an onrushof material through the slots 28 with the water flowing therethrough,the edges of the plates 34 paralleling the adjacent side edges of theslots, are bent outwardly, as indicated at 38.

In the drawings, the plates 34 are shown as only partly covering oroverlying the slots 28. However, should it be desirable to nearly closethe openings through the slots, the plates can be shifted further to theright, as viewed in Fig. 5,

in which position the outwardly bent portion 38 will overlap the portionof the helical band 2| to the right of the slots 28. Also, it will beunderstood that the openings 31 may be so disposed in the plates 34 thatsaid plates can be so located with respect to the slots 28 as to varythe depth of the opening of said slots, as well as the width g th5eslots, as is illustrated by dotted lines, in

When the oversize material is comparatively 30 coarse, obviously theplates 34 can be positioned with respect to the slots 28 so as to permita considerable amount of water to flow through the slots withoutcarrying with it an undesirable quantity of material. On the other hand,the 35 material will be prevented from flowing back with the water inobjectionable quantities.

Instead of discharging the oversize directlys from the compartment 23 tothe discharge lip 3|, the classifier can be formed with an enlargeddischarge head 40, as shown in Figs. 7 and 8.

This discharge head contains a plurality of buckets 4| which function aselevators that scoop up the material and deposit the same into adischarge trough 42. The trough 42 extends downwardly through an opening43 in the outer 5 end wall of the head 40 and terminates over a chute44.

The left hand or front end of the drum opens directly into the head 40.The helical trough 2| terminates adjacent to the junction of the drum IIwith the head, so that the material, in moving forwardly through thedrum is forced by the last flight 45 into the bottom of the head 40.

The buckets 4| may be so constructed that the material deposited in thebottom of the head 40 is readily picked up and carried upwardly to apoint above the level of the water in the classifier whereby the waterquickly drains from the elevated material before such material isdischarged from the buckets.

As shown in Fig. 7 the feed water pipe 33 may terminate in the dischargehead 48. However, it should be noted that when so desired, said pipe canextend through the head 40 and terminate in the main classifying chamberof the drum The point at which the feed water pipe 33 terminates dependsentirely upon the kind of material being classified. Thus, should thema'-'- terial delivered to the discharge head 40 from the.

main classitying chamber contain an undesirable quantity oi slimes,dirt, etc., it will be advantageous to deliver the wash water into thedischarge head 40, so that the oversize material will be furthercleansed. On the other hand. should the .oversize' material beingdischarged trom the drum H into the head 40 be comparatively clean, andrequire no further washing,

shown in Fig. 1.

then the water pipe 33 can extend through the head 40 and terminate overcompartment 23, as

In this case the oversize material in the head 40 will be substantiallydewatered, since very little wash water will fiow therewith past the end45, on account of the drains provided by the slots 28 and the dam eflectoi. the successive compartments.

Having thus described my invention, what I claim is:-

1. A classifier comprising a rotatable classifying chamber having endwalls, a fines discharge opening in one end wall of said chamber, anoversize material discharge opening in the opposite end wall of saidchamber, and a helical band disposed around the interior of said chamberfor moving material towards said oversize discharge opening, said banddecreasing in pitch and increasing in depth from the fines discharge endtoward the oversize discharge and of said chamber, the decrease in pitchof said band being at a greater rate than the increase in depth withrespect to the volume, whereby the net volume of material carried by theband constantly decreases and is zero where the band terminates at theoversize discharge end wall of the chamber.

2. A device of the class described comprising a rotatable drum having animpervious wall, a helical trough fixed to the interior of the drum andadapted to prevent the passage oi. water and other matter along theinner surface 01' the drum, the height oi said trough graduallyincreasing from one end of the drum towards the other, means forsupplying wash water to the drum, and notches formed in the highestportion of said trough, said notches extending downwardly of the troughvarying distances, the notches in the portion of the trough of greatestheight being deeper with respect to the height of the trough than thedepth of the notches formed in said trough rearwardly of the end of thedrum, whereby liquid in the material in the highest portion of thetrough can drain backwardly towards the opposite end of the drum.

3. A device of the class described comprising a rotatable drum having animpervious wall, means for supporting the drum in a position tilted fromthe horizontal, means for rotating said drum, a screw flight fixed tothe interior of the drum and adapted to prevent the passage oi. liquidalong the inner surface of the drum, the pitch of said screw flight atthe lower portion of the drum being relatively steep for rapidlyadvancing material toward the upper end of the drum when the drum isrotated, and notches in one end portion or the screw flight for drainingliquid in the portion of the drum at the upper end thereof back towardsthe lower portion of the drum, said notches extending downwardly intothe screw flight varying distances, the notches formed in the portion ofthe screw flight of greatest height being deeper with respect to theheight of the screw flight than the depth of the notches formed in saidscrew flight rearwardly of the upper end of the drum.

end through which fines and liquid are discharged, an opening at thefront end of the drum through which oversize material is discharged, ahelical band extending through the drum and adapted to prevent thepassage of liquid along the inner surface of the drum, said helical bandbeing adapted to convey material delivered into the rear end of the drumtoward the front end thereof, means for supplying liquid to the drum.said helical band gradually increasing in depth from the rear endtowards the front end of the drum, the portion or said band adjacent therear end or the drum being submerged by liquid in the drum, the portionof the trough adjacent the front end of the drum extending above theliquid in the drum, said drum having an impervious wall, and means fordraining liquid from material in the portion of the helical bandadjacent the front discharge end 01' the drum back towards the reardischarge end of the drum comprising notches formed in the portion ofsaid band adjacent the discharge end of the drum, said notches extendingdownwardly into the band varying distances, the notches formed in theportion 01' the bond of greatest height being deeper with respect to theheight of the hand than the notches formed in said band rearwardly orthe discharge end of the drum.

5. A classifier comprising a rotatable drum having a fines and liquiddischarge opening at one end and an oversize discharge opening at theopposite end, a helical band for moving material through the drum fromthe fines discharge end towards the oversize discharge end of the drum,means for supplying liquid to the drum, and openings formed in thehelical band adjacent the oversize discharge end of the drum fordraining liquid from compartments between said band back towards saidfines discharge end, said openings extending downwardly into the helicalband varying distances and terminating above the wall of the drum, theopenings formed in the portion of the helical band adjacent the oversizedischarge end of the drum being deeper with respect to the height ofsaid band than the openings formed in said band rearwardly of theoversize discharge end.

6. A classifier comprising a rotatable classifying chamber having endwalls, a fines and liquid discharge opening in one end wall of saidchamber, an oversize discharge opening in the opposite end wall oi saidchamber, said chamber hava ing an impervious outer wall, a helical banddisposed around the interior of said chamber for moving material towardssaid oversize discharge opening, said band being adapted to prevent thepassage 01' liquid along the inner surface of said chamber, said banddecreasing in pitch and increasing in depth from the fines discharge endtowards the oversize discharge end of said chamber, the decrease inpitch oi said band being at a greater rate than the increase in depthwith respect to the volume, whereby the net volume of material carriedby the band constantly decreases and is zero where the band terminatesat said oversize discharge and wall of the chamber, and notches formedin said band adjacent the discharge end of said chamber for drainingliquid from the material, said notches extending downwardly into thehelical band varying distances, the notches formed in the portion of thehelical band of greatest height being deeper with respect to the heightof the band than the notches formed in said band rearwardly oi. theoversize discharge end of said chamber.

'I. A classifier comprising a rotatable classilying chamber having endwalls, a helical band mounted in said chamber and adapted to prevent thepassage of liquid along the inner surface of the chamber, said chamberhaving impervious walls, one of said end walls having a fines dischargeopening formed therein, an opening formed in the opposite end wallthrough which the oversize material is discharged, an enlarged headattached to the oversize discharge end or said chamber, means in saidhead for elevating the material delivered thereto from said chamber andfor discharging the same from the classifier, the oversize dischargeopening being greater in diameter than the internal diameter of saidband at the point where said band terminates adj acent to said oversizedischarge end of saidchamher, the convolutions of said band varying fromthe fines discharge end towards the oversize discharge end, whereby thenet volume of material carried by the band constantly decreases, meansfor feeding material and liquid into said cham her, and notches formedin the portion of said band of lesser volume for draining liquid fromthe material back towards said fines discharge end of the classifier,said notches extending downwardly into the band varying distances, thenotches in the end portion or the band being deeper with respect to theheight of said band and all of said notches terminating above the wallof said chamber.

8. A classifier comprising a rotatable drum mounted on an inclined axisand having annular end walls providing central openings for the drum,the opening in the lower end wall serving as a fine material dischargeopening and the opening in the upper end wall serving as an oversizematerial discharge opening, and a hellcal band disposed around theinterior of the drum for moving material towards the oversize dischargeopening, said band extending the entire length of the drum andterminating in contact with the upper end wall of the drum, said banddecreasing in pitch and increasing in depth from the fines discharge endtoward the oversize discharge end of said drum, said oversize dischargeopening being greater in diameter than the opening through the band atthe discharge end oi the drum 9. A classifier comprising a rotatabledrum mounted on an'inclined axis and having annular end walls providingcentral openings for the drum, the opening in the lower end wall servingas a fine material discharge opening and the opening in the upper endwall serving as an oversize material discharge opening, a helical banddisposed around the interior of said drum for moving material towardssaid oversize discharge opening, said band extending the entirelengthvof the drum and terminating in contact with the upper end wall ofthe drum, the band increasing in depth from the fines discharge endtoward the oversize discharge end of the drum, said oversize dischargeopening of the drum having a diameter greater than the diameter of theopening through the band at the oversize discharge end of the drum,meanstor supplying liquid to the drum, and openings formed in thesections of the band adjacent the discharge opening for draining liquidfrom material backwardly towards the opposite end of the drum.

10. A device of the class described comprising a rotatable drum mountedon an inclined axis and having annular end walls providing centralopenings for the drum, the opening in the lower end wall serving as afine material discharge opening and the opening in the upper end wallserving as an oversize material discharge opening, a helical band fixedto the interior of the drum and adapted to prevent the passage of waterand other matter along the inner surface of' the drum, said bandextending the entire length of the drum and terminating in contact withthe discharge end wall of the drum, the height of said band graduallyincreasing from the fines discharge end towards the oversize dischargeend of the drum, means for supplying wash water to the drum, and notchesformed in the oversize discharge end portion of said band, said notchesextending downwardly into the band and terminating above the innersurface 01' the drum for draining liquid from the material in theportion of the band adjacent the oversize discharge end oi the drumbackwardly towards the opposite end of the drum.

HARLOWE HARDINGE.

